There are numerous industrial processes that produce gas streams containing carbon dioxide, hydrogen sulfide, hydrogen chloride, nitrogen oxide, and sulfur oxide. It is often desirable to remove one or more of these gases from the other components of the gas streams, such as hydrogen and nitrogen. Inorganic membranes have been employed for a variety of gas separation applications, including hydrogen purification and carbon dioxide sequestration. However, a major limiting factor to the application of inorganic membranes is the frequent occurrence of defects which limits reproducibility, stability, and the separation performance of the membranes. There remains a need in the art for membranes, methods of making membranes, and methods of separating gases.